Update on Partial Breast Irradiation

Invasive lobular breast cancer: Focus on prevention, genetics, diagnosis, and treatment

Invasive lobular cancer (ILC) is the most common of the breast cancer special types, accounting for up to 15% of all breast malignancies. The distinctive biological features of ILC include the loss of the cell adhesion molecule E-cadherin, which drives the tumor's peculiar discohesive growth pattern, with cells arranged in single file and dispersed throughout the stroma. Typically, such tumors originate in the lobules, are more commonly bilateral compared to invasive ductal cancer (IDC) and require a more accurate diagnostic examination through imaging. They are luminal in molecular subtype, and exhibit estrogen and progesterone receptor positivity and HER2 negativity, thus presenting a more unpredictable response to neoadjuvant therapies. There has been a significant increase in research focused on this distinctive breast cancer subtype, including studies on its pathology, its clinical and surgical management, and the high-resolution definition of its genomic profile, as well as the development of new therapeutic perspectives. This review will summarize the heterogeneous pattern of this unique disease, focusing on challenges in its comprehensive clinical management and on future insights and research objectives.

Preoperative Breast MRI: Current Evidence and Patient Selection

Breast MRI is the most sensitive imaging modality for the assessment of newly diagnosed breast cancer extent and can detect additional mammographically and clinically occult breast cancers in the ipsilateral and contralateral breasts. Nonetheless, appropriate use of breast MRI in the setting of newly diagnosed breast cancer remains debated. Though highly sensitive, MRI is less specific and may result in false positives and overestimation of disease when MRI findings are not biopsied prior to surgical excision. Furthermore, improved anatomic depiction of breast cancer on MRI has not consistently translated to improved clinical outcomes, such as lower rates of re-excision or breast cancer recurrence, though there is a paucity of well-designed studies examining these issues. In addition, current treatment paradigms have been developed in the absence of this more accurate depiction of disease span, which likely has limited the value of MRI. These issues have led to inconsistent and variable utilization of preoperative MRI across practice settings and providers. In this review, we discuss the history of breast MRI and its current use and recommendations with a focus on the preoperative setting. We review the evidence surrounding the use of preoperative MRI in the evaluation of breast malignancies and discuss the data on breast MRI in the setting of specific patient factors often used to determine breast MRI eligibility, such as age, index tumor phenotype, and breast density. Finally, we review the impact of breast MRI on surgical outcomes (re-excision and mastectomy rates) and long-term breast recurrence and survival outcomes.

Facility-Level Variation of Low-Value Breast Cancer Treatments in Older Women with Early-Stage Breast Cancer: Analysis of a Statewide Claims Registry

BACKGROUND

Since 2004, national guidelines have supported the omission of sentinel lymph node biopsy (SLNB) and radiotherapy for women ≥ 70 years of age with early-stage, hormone receptor-positive (HR+) breast cancer, but many women continue to receive at least one of these services. Provider- and patient-level factors may contribute to persistent utilization, but the role of facility-level factors is unknown. We aimed to determine facility-level variation of SLNB and adjuvant radiotherapy utilization in older women with early-stage, HR+ breast cancer undergoing breast-conserving surgery (BCS). Additionally, we aimed to explore factors associated with SLNB and radiotherapy utilization and the intra-facility correlation in their utilization.

METHODS

We conducted a retrospective cohort study using a statewide registry of claims data. We included women ≥70 years of age diagnosed with breast cancer who underwent BCS from 2012 to 2019 at 80 hospitals in the Michigan Value Collaborative. The main outcome was inter-facility rates and variation of SLNB and radiotherapy, as well as intra-facility correlation in their utilization.

RESULTS

The cohort included 7253 women (median age 77 years). Only 20% (n = 1440) underwent BCS alone, whereas 71% (n = 5122) underwent SLNB and 52% (n = 3793) received radiotherapy. Inter-facility rates of SLNB ranged from 35 to 82% (median 70%), and radiotherapy ranged from 19 to 72% (median 49%). SLNB and radiotherapy were positively correlated (r = 0.27, p = 0.016).

CONCLUSIONS

SLNB and radiotherapy rates remain high with significant variation in utilization at the facility level. High utilizers of SLNB are likely to be high utilizers of radiotherapy, suggesting the opportunity for strategic targeting of these facilities and their clinicians.